Foldable, erectable paperboard cartons or containers have long been recognized as an inexpensive and efficient way to contain many materials for many purposes. Over the years, cartons have been provided with specific features depending on the use of the carton, both in terms of the material to be contained therein and in terms of handling the carton itself.
One area of prior work has been the development of cartons and material for forming cartons for containing hygroscopic material or other materials requiring a degree of barrier, such as various soap powders, sweeteners or pancake mixes. This type of container is particularly adapted to prevent the absorption of moisture by the material contained in the carton and also to prevent leakage of the material, by having, for example, films or other coatings applied to or integrated with the carton walls. Sifting can be a particular problem, because the materials are typically in powder or fine granulated form and as such, easily penetrate unsealed seams or perforated lines on the carton having cuts that penetrate completely through carton walls, if the materials are in direct contact with the cuts and the cuts lead directly to the outside.
There have been attempts in the prior art to provide a container that addresses the above concerns. U.S. Pat. No. 4,732,315 discloses a recloseable dispensing package that has a plastic fitment mounted over a cutout area in one flap and an overlying closure flap. Another structure for forming a recloseable opening in a carton for containing a hygroscopic material is present in U.S. Pat. No. 4,718,557, wherein an outside panel may be opened to expose a weakened region that may be partially or fully severed from an inside panel. Also representative of the prior art is U.S. Pat. No. 1,303,138, which discloses a carton with a hinged flap that overlies pouring perforations in an inner flap.
U.S. Pat. No. 3,346,165 discloses an easy opening recloseable container including a dispenser for dispensing the contents. In particular, a portion of the container, severable along perforated lines to form a hinged flap, overlies an opening.
U.S. Pat. No. 2,819,832 discloses a leakproof carton having superimposed inside and outside spout openings. However, when double perforated flap structures are used, the material contained in the carton may still leak out and moisture may easily penetrate the carton, leading to contaminated contents, when the perforations are through cuts and cuts in separate layers are adjacent or superimposed. Thus, such prior art structures lack desired barrier qualities.
A carton having a double panel end closure with an opening flap in the outer panel providing access to a dispensing aperture in an inner panel is shown in U.S. Pat. No. 4,909,395. The opening structure includes a partially pre-cut bridge in the adhesive area for securing the outer opening flap to the inner panel. One problem with opening features of the type shown in this and other prior patents is that coating materials or adhesives used between inner and outer panels may penetrate the perforations or scores or be inaccurately applied, thereby interfering with opening the carton. Also, cuts that run from the carton exterior to the inner opening can provide a path for moisture entry.
For some packages, particularly those that contain foodstuffs, it is desirable to have an opening structure that can provide evidence of possible tampering. The prior art includes packages in which opening involves tearing a perforated line or removing a tab or band that blocks access to the dispenser opening. U.S. Pat. No. 1,424,127 shows a box with a sticker used to seal the cover in a closed position. U.S. Pat. No. 4,569,443 shows a carton with a pouring spout that includes a removable access tab that provides a means that for determining whether tampering has occurred. U.S. Pat. Nos. 3,395,848, 4,706,875 and 4,799,594 all show recloseable opening and dispensing structures for cartons in which the perforations or other lines of weakening used to form a portion of the structure will help to evidence tampering if they appear to have been torn.
Despite the above-cited prior art, there remains a need for a carton for packaging powdered materials that prevents leakage and provides barrier protection for the material contained in the carton, while at the same time providing tamper evidence and a pour spout that is easy for a consumer to open. Further, it is desirable for such a carton to be easy to reclose and that the reclosed opening be effective to limit significant entry of air, which might affect the powdered materials.